//////////////////////////////////////////////////////////////////////////
//
// Simple OpenGL program to draw a hollow blue square of dimension 40x40
// The white portion is of dimemsion 20x20
//
//////////////////////////////////////////////////////////////////////////
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
using namespace std;

#define numVAOs 1

GLuint renderingProgram;
GLuint vao[numVAOs];

GLuint createShaderProgram() {
	const char* vshaderSource = 
		"#version 430    \n"
		"void main(void) \n"
		"{ gl_Position = vec4(0.0, 0.0, 0.0, 1.0);}";

	const char* fshaderSource =
		"#version 430    \n"
		"out vec4 color; \n"
		"void main(void) \n"
		"{ if (gl_FragCoord.x > 290 && gl_FragCoord.x < 310 && gl_FragCoord.y > 290 && gl_FragCoord.y < 310) color = vec4(1.0, 1.0, 1.0, 1.0); else color = vec4(0.0, 0.0, 1.0, 1.0);}";

	GLuint vShader = glCreateShader(GL_VERTEX_SHADER);
	GLuint fShader = glCreateShader(GL_FRAGMENT_SHADER);
	GLuint vfprogram = glCreateProgram();

	glShaderSource(vShader, 1, &vshaderSource, NULL);
	glShaderSource(fShader, 1, &fshaderSource, NULL);
	glCompileShader(vShader);
	glCompileShader(fShader);

	glAttachShader(vfprogram, vShader);
	glAttachShader(vfprogram, fShader);
	glLinkProgram(vfprogram);

	return vfprogram;
}

void init(GLFWwindow* window) {
	renderingProgram = createShaderProgram();
	glGenVertexArrays(numVAOs, vao);
	glBindVertexArray(vao[0]);
}

void display(GLFWwindow* window, double currentTime) {
	glUseProgram(renderingProgram);
	glPointSize(40.0f);
	glDrawArrays(GL_POINTS, 0, 1);
}

int main(void) {
	if (!glfwInit()) { exit(EXIT_FAILURE); }
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	GLFWwindow* window = glfwCreateWindow(600, 600, "CS535-2025f-HW2-Q3", NULL, NULL);
	glfwMakeContextCurrent(window);
	if (glewInit() != GLEW_OK) { exit(EXIT_FAILURE); }
	glfwSwapInterval(1);

	init(window);

	while (!glfwWindowShouldClose(window)) {
		display(window, glfwGetTime());
		glfwSwapBuffers(window);
		glfwPollEvents();
	}

	glfwDestroyWindow(window);
	glfwTerminate();
	exit(EXIT_SUCCESS);
}